January Freeze May Eliminate Some Citrus Fruit

           I know I will get questions sent to me why their lemon or grapefruit did not produce any fruit this year. They will say, “The tree grew great, but it didn’t produce any fruit!” We had a pretty good freeze in parts of the Valley recently. If your lemon tree or other citrus had flowers, or very small fruit at that time, then that’s why.

Freeze Tolerance of Flowers vs Tree

            Citrus, the entire tree itself, is tender to freezing temperatures in the first place. It’s considered subtropical. The most tolerance to freezing temperatures starts with kumquat, then Myers lemon, grapefruit, followed by some of the oranges, true lemons and finally limes. Freezing damage results in temperatures ranging from about 22° F to 32° F.

            As soon as growth begins, tolerance to freezing temperatures decreases in entire trees. This holds true of all fruit trees. There is no temperature discrimination when the tree is flowering. All fruit tree flowers and young fruit, whether they are apple or citrus, will die when it freezes. Freezing occurs at 32° F. No exception.

            All flowers are tender to freezing temperatures. All fruit trees flowering during freezing temperatures result in dead flowers and no fruit. The tree survives at 32° F, but the flowers don’t. Young fruit trees are more sensitive to cold temperatures than older ones.

Wind Makes Freezes Worse

            Add a light wind to this formula, flowers and fruit for that year are history. There is a debate whether plants succumb to “wind chill” like humans and animals. Let the debate rage. But I guarantee you, if there is wind associated with any freezing temperature, there is more damage than if there were no wind at all. Protect food production areas of the landscape from wind.

            You are lucky. If you don’t like a cold north wind, you go inside the house and get warm. Plants can’t. They must “suffer” through it. Therefore, let them occupy protected spaces in the landscape and they will be more productive and produce better quality food.

Arizona State University's citrus variety descriptions and harvest times.

            Remember, there are microclimates in a landscape. South and west sides are warmer locations than north and east sides of the home. Protect the tree from wind and you have a nice small, warm microclimate that produces better food.